Electric valve excitation circuits



Aug. 19, 1941. l A, w, HULL l 2,253,180 ELETRIC VALVE EXCITATION CIRCUITS Filed Sept. l, 1939 2 Sheets-Sheetl NSULATED is ttohney, A

Aug. 19, 1941.

A. w. HULL ELECTRIC VALVE EXCITATION CIRCUITS Filed sept. 1, 4193,9 2 sheets-shed 2 ALLlc ENVI-:LOPE

. Inventor: 'Albert W. Hull,

MWL! byjl/mtorney Patented Aug. 19, 1941 i. azaiso Albert -W.f Hu1l,fSch enectady,.N. Y., assigner to iGeneraLElectric TCompany, a .corporation of c npplieationfseptember 1, 1939; serial No. 293,076

isciaims. (c1. 17e- 363) My invention relates 'to "electric" -valve i circuits and more `particularly to control-lor excitation circuits "for energizing 'the control members of electric valve apparatus.

`Where `"electric vvalve apparatus fo-f fthe type employing immersion-ignitor "controlimembers or make-alive control members isi-used, I it 'has-been "ffound desirable in manyinstances to supply? only unidirectional impulsesef current toi'the control members-to initiate the`-farc fdischarge. A"In electric valve apparatusof this nature; disclosed and claimed in Un-Sl Letters"Patent"` No.12 ,069,283,

" grantedf4February"72,` 1"-9'37, "on-an Aapplication of t J. Slepian land"'I if'l.. Vliudwig;1it"l1:1;s been ffeund that `the llife foi the electric valve apparatus may be materially increased* by transmitting only unil directional current to thecontrol members. The

control `members Lha-ve '-an extremity `extending "below the 'surface o'f thelpoolfcathddei'and@may "be `constructed of'f'a material" havinga `specific electrical resistivity relativelylarge @compared with that J'of *the "associatedcathede For `example,` the "control membersmayfbe constructed ci a material"such as -boronecarbide orfsiliconcarbide. -In accordance'with the teachings of my invent-ion Fdescribed *hereinaiter, "I provide new and improved -cor`itrol `circuits rfor-"electric valve apparatusfcf this `'nature whichlisef siniple 'construction and*arrangement and which af- `fords precise-'and accurate 'control `of the 'conductivityof*theelectric valve apparatus.

`It is an Lobject of my invention to provider new and improved electric valve'ltranslating -apparatus. u

`It is another objecto'f my invention' to provide new and improved Acontrol ore rcitati1on` circuits "for electric va-lve mea-ns ofthe type employing make-alive or immersion-ignitor control 'members.

"It is a `further "obje'ctf-lmy invention to provide new andimproved controler `excitation circuits"iorelectric Valvefmeans f the *type eimploying makealive eleetro'desla-Iid in which only lunidirectional impulses of `current are iltransvmitted to 'the' control* members. i

Brieiiy described;v in the @illustrated embodiments of my invention "I `prov-ide new andimproved controlor excitation 'circuitsffor electric valve means of the type employing immersionignitor or make-alive control members The electric valve apparatus is arranged to dispense with the useof `separate "auxiliary rectifying equipment, While `nevertheless transmitting to I thelcontrcl` members undirectonal impulses of current which render thefelectric kvalvemeans conductive for Aa predetermined interval of time and in `a predetermined order. Associated equipmenhsuch aspeaking'devices, `are connected-in the excitation circuits to supply -impulses ofvoltage to render the `electric valvesconductive precisely at the `desired instants, andthe `electric `valve means operate in *conjunction with "the .peaking devices to transmit only unidirectional impulses of current to the controlmembers.l

reference may be hadto the following descrip- "tion taken in connection with tliefa'ccompanying drawingsfandits scope Will'be'pointed out in the appended claims. Figs. A1 `and 2 represent 'certain 'embodiments' of A'myinvention as applied to an electric `valve rectifying "circuitwherein an isolated collectonor` grid is interposed between the `anode "and cathode `of theprincipalelectric "valvefmeans tooperate as the auxiliary rectifyingdevicafand Fig. 3 represents Ycertainoperatfing characteristics thereof. Fig.` 4 representsa #still 'further modicationof "my invention in `which the metallic enclosing receptacle of the electric valve means operates in conjunctionwith the insulated cathode to transmit unidirectional impulses of current to the control member of another electric v'alve in the group of velectric valves. Referringfno'w to Fig.- 1 of the drawings, my

invention is there illustrated las appliedtofan electric' valve translating circuit for transmitting i power between an alternating current circuit l andra direct current circuit 2 through a transformer@ having a pluralit'yof primary windings 4 and a plurality of secondary windings 5,6 and 1 which constitute `an inductive network of "electrically displaced windings. -I` provide a plurality `of electric valve means 8, 9 and 4I() associated -with windings'"5,6 and 1,respectively, and which transmit Vunidirectional current. The electric valve means 8, 9 and I -are preferably `of the type employinglan ionizable "medium, such as `a gasor a vapor,` and each V'comprises a cathodel I of thepool type. The Vcatl'iode Hmayfconsist `of mercury which, of course, constitutes a selfreconstructing cathode. Each of the electric Valve means ii-I0 comprises a make-alive or "an immersion-ignitor control member AIZ associated with the lcathode I I and which is constructed of a material such as boron-carbide or Vsilicon-carbide 'having an electrical resistivityrrelatively large "compared with that of the associated cathode.

One ofthe electric valve means -i may be provided `with suitable arc initiating means in `order toplace thefsystem in condition for op- L eration. It wiurbe appreciated by tnoseskiued in the art that any conventional arrangement for establishing an arc discharge may be employed. I also provide within the electric valve means 8-IIl an insulated collector or grid I3 which may be interposed within the arc discharge path between the anode I4 and the cathode II. It is not necessary that the collector or grid be an actual grid in construction or that it should be directly interposed between the cathode and the anode; it may have any form and any position provided that it is immersed in the ionized gas during the firing or conducting period of `the electric Valve. When the word grid is used, it is to be understood in this sense. The grid I3 is insulated with respect to the cathode I I and its function is the establishment of a conducting path between itself and the cathode II at a predetermined time during its cycle of operation to effect energization of a control member of one of the other electric valves Q or III.

I provide a plurality of excitation circuits I5, I6 and Il associated with electric valves 8, 9 and I0, respectively, and which transmit to the control members I2 impulses of unidirectional current to establish arc discharges within the electric valve means and thereby render the electric valve means conductive in a predetermined order or sequence. Each of theexcitation circuits I-I'I comprises a suitable means for producing impulses of voltage, such as a saturable inductive device I8 including a core member I9, a primary winding 20 and a secondary winding 2| in which there is induced an alternating voltage of peaked wave form. The excitation circuits I5--I'I may be energized from any suitable source of alternating current of proper frequency and which provides the desired phase relationship of the voltages to be impressed on the control members I2. The excitation circuits in the embodiment of my invention shown in Fig. 1 are shown as being f' energized from the alternating current circuit I. A suitable phase shifting arrangement, such as a rotary phase shifter 22, may be interposed between the circuit I and the excitation circuits I5-I'I.

As a means for assuring that only unidirectional current is transmitted to the control members I2 and to dispense with the use of separate auxiliary rectifying equipment, I connect the secondary windings 2| of the saturable inductive devices I8 between the control member of one electric valve and the grid of that electric valve preceding it in the order of phase rotation. For example, the secondary winding 2I of the device I8 associated with electric valve 8 is connected across control member I2 of electric valve 8 and the grid I3 of electric valve IIJ which precedes the electric valve 8 in the order of conduction. Like- Wise, the control member I2 of electric valve 9 is connected through the secondary winding ZI of the saturable device I8 in excitation circuit I 6 to the grid I3 in electric valve 8, the electric valve 8 preceding the electric valve 9 in the order of phase rotation.

The operation of the embodiment of my invention illustrated in Fig. 1 will be explained by considering the system when it is operating as a polyphase rectier to transmit direct current to the circuit 2 from the alternating current circuit I. For the purpose of explaining the operation of the excitation circuits I5-I'I, it will be assumed that the voltages of the secondary windings 5, 6 and I of transformer 3 have a phase rotation corresponding to' that order; that is, the voltages assume their respective maximum positive values in that order. Consequently, the electric valves 8, 9 and IG will conduct current in that order and each will conduct current for electrical degrees inasmuch as the windings 5-1 constitute a three phase system. As is well understood by those skilled in the art, each of the electric valves 8-IIl will conduct current until the electric valve following it in the order of phase rotation is rendered conductive, at which time current will be commutated to the electric valve which is rendered conductive by virtue of the fact that its anode is more positive in potential than that of the electric valve which was previously conducting. In the present instance, the electric valves are rendered conductive by the transmission of current to the control members I2 to establish on the surface of the mercury pool cathode II a cathode spot, thereby establishing an arc discharge between the cathode II and the anode I 4.

Each of the saturable inductive devices I8 or excitation circuits I5--II produces an alternating voltage of peaked wave form. These voltages are displaced in phase by 120 degrees due to the connection of the primary windings 20 in the three phase circuit I. However, due to the fact that each of the secondary windings 2I is connected in series relation with an arc discharge path of another electric valve, only unidirectional current will be transmitted to the control member. That is, since the secondary windings 2I are connected to the grids I3 of other electric valves, the other electric valves operate as rectifying units for the control members.

Consider the operation of the system when one of the electric valves, as for example electric valve 9, is to be rendered conductive during the 120 electrical degree period following the normal period of conduction of electric valve 8 and electric valve 8 has been conducting current. Consequently, the ionizable medium of the electric valve 8 is in an ionized state and current may flow between the cathode II and the grid I3. As a result, when the voltage induced in the secondary winding 2| of the inductive device in excitation circuit I6 increases suiciently to transmit an appreciable current to the control member I2 of electric valve 9, substantially only unidirectional current will be transmitted to that control member since the grid I3 and cathode I I of electric valve 8 operate in effect as an auxiliary rectifier. As soon as the electric valve 8 becomes nonconductive by the commutation of current to the electric valve 9, the circuit for the energization of the control member I2 of electric valve 9 will be interrupted since the mercury vapor of valve 8 becomes de-ionized. In this manner only unidirectional impulses of current are transmitted to the control members and the circuits for the energization of the control members are interrupted as Soon as the electric valve is rendered conductive and current has been commutated to that valve. Since only unidirectional current is transmitted to the control member, the duty imposed on the control member is substantially reduced and the life of the electric valve means is greatly increased.

Where it is desired to assure that the potential of the control members I2 is always maintained positive with respect to that of the associated cathode II, I provide, as shown in Fig. 2, means for introducing into the excitation circuits I 5-I 1 voltages to assure that no inverse current ows between the control members I2 and the cathodes II. I provide suitable means, such as transfarmers-i123, connected in f.',excitation `:circuits l Iii-,|51 'zto impress non V.the control Y:inem-bers 'ritz @positive `r voltages to :maintain "the :control `finem- `bers` rpositive @with :respect to the cathoiies rlsl. This -'.voltage :may tbe .fprovided nin .ra '.vnumber of -ways andi 5I l-havefchosen;:forethepurposes, of illusztration, to `show alternating:currentrmeans, .such as ntransformers, ienergizled :from the :gralternating m.current circuit 'l through :arsuitable :phase .shifting rdevice fsuch .as .a rotary :phaser'shiiter Milfor @energizing ;;the -gt-ransfprmers @2;3. The .rotary phase .1 Shifter .2.4 x is :adjusted :so that "fthe nvoltage `introduced into @each excitation circuit is 'ssuch `.that the resultant` voltaeefimpressed .on teach .of .the -control imemhers .it-2 :is positive` during :the .entireginterval'rof time during which :its =asso .ciated excitation .circuit fis :completed :through l the electric Lvalve'which precedes? it :.inithe `.order of `phase rotation.

'The manner in -Nvhioh tthe excitation circuits `shown ,in Fig 2 operate may `ille fmore fully .understood by referring to.theoperating-characteristics shown in .-Fig. k3. Curve `A Arepresents :the voltage of peaked Wave form A 'produced by the saturable finductivev device rI in `one of the `excitation zcircuits, `such as fexcitation circuit `4I-6 .associated=With-electricvalve 9. It/will be under- ,stood .that `the positive impulsesof voltage-represented by `1Curve -A.occ.ur.360` electrical degrees apart. .-For example, :the electric yvalve '19 lis fren- .der-ed conductive atftimes a-zandfc. Furthermore, it will :be :understood l.that @electric Naive ,9 :conducts `current .on1.y 1120.\e1ectrical `degrees during teach :cycle Alurthermorel fit .-Will be M:appreciated that theelectric valve B-is rendered vconductive at v.time b rand lthat-itne electric valve 8 conducts `current rduring the interval During the interval of .time that the Yelectric valve .-8 `conducts .-it will be iappreciated, Vdoy rreferring to -the curves of Eig.` 3, that van ,inverse voltage may .be

impressedon :the control member I2-'of `electricvalve 9. tif -no auxiliaryquipment weresemployed. .By the `proper adjustment of the `rotary fphase .shifter '24, rthe component :of voltage Aintroduced into excitation `circuit t6. by transformer .23 f-may .be -adjusted'in phase fso that .at alltimes during .the interval bf-c-.the resultant `.voltage impressed .onfcont-rolmernber lf2 is positive. Inlthis manlner 4the `transmission fof inversecurrent ibetween the control member I2 and fthe cathode `I-I is..

.prevented .and the ilife of the .electric valve is correspondinglyincreased.'

.'Fig. .4 .illustrates .assimplified .embodiment of my invention as applied `.to a .system similar lto L-thatsshown in Fig. A1` andcorresponding elements havebeen assigned 4.like ,reference numerals. In- .steadloffemploying separate auxiliary grids which cooperate withgthecathodes to rectify the exci- `.tation `currents transmitted .to .thescontrol membersfI femployelectric .valves 12,5, .26 ...and .21 fwhich .comprise Vmetallic 4@enclosing envelopes -`=28 and electricallyfinsulated cathodes 2B. The cathodes .2 8 may ,be insulated .from ythe ...envelopes .2.8 .by means of suitable insulating means, ysuch as in- `sulator rings-30, positionedrbetween the upper portionfof the envelopes and the cathodes. That is, the cathodes efareelectrically insulated from the envelope 2;8.. Accordingly, the envelope K28 may' be employed as one electrode of an auxiliary rectifying unit. Iconnect the secondary winding 2I of each of the inductive devices I8 to the metallic envelope 28 of that electric valve preceding it in the order of phase rotation. One of the important features of this arrangement is the simplicity of construction and the incident re- 111'0 `.catliodesilfiwhich* operate asfauxiliary rectiers,

`.and .whiclneiect :completionof :the excitation. cir- Ycuits:'ior'xthe controlrmembers -I2 `until the electric .valvezprecedingit in the orderfof'phase rotation flras been 'rendered nonconductive yby the "-.15 commutation fof :currenttherefrom "While I Shave s'hown and described my inventiontas rapplied irto m.particular systems of connections: and zas embodying :various :devices dial ;zgrammaticallyshown, it willnbe .obvious to those :2o @skilled inthefart-thatchanges Vand modincations may be made Without departing from my inven- `-tion,rand eI, "..therefore, iaim .in the appended 'zolaims .1t-o cover :all such .changes and modifications :aiszfall .within the i true spirit and 'scope of zinyrinvention.

Miiagt-I :claimns .new and ,desire to secure by 'LetterssBatent of `fthe United States is:

'21. .Intcombination, fan alternating .current cirouitn-.a :idirect current tcircuit, "electric translating 4apparatus connected between said lcircuits and :comprising an inductive .network including a -pluralitynf electrically .displaced windings and :ia pluralityof .electric valvesV of 1 the `type `employring an eionizable medium `and `each 'associated zwlthiadifferentvone-of ysaid lwindings and each `fcomprising fan anode, a cathode, van `immersioniig'nitor i:control member associated with `the :cathode and'means insulated from said cathode forfestablishinga:conducting pathto said lcathode ithrough said :medium `when said 'medium is `ionized, and a plurality of means ifor supplying to #therc-:ontrol members periodic impulses of unidi- :rectionalicurrent and'eachcomprising a source oflcurrent'including 'a :Winding 'having one termindliin circuit @with :the `control member of the associated electric valve fand `having the other terminal connected -to -the insulatedmeans of that -e1ectric `valve'preceding it in the order of phase rotation.

A2f-11n combination, an alternating current cir- -cuit, ak direct current circuit, electric translating Iapparatus connected between said circuits and comprising an'in'ductive network including a plurality'o'f electrically displaced windings and a plurality fofelectric valve means each associated with -a diierent 'oneof saidwindings and each comprisingan anode, a cathode, an immersionignitor lcontrol member associated with the 4cathojde'and a `grid interposed -in the arc discharge path between said anode and said cathode, meansrfor supplying to the control membersperiodic impulses of unidirectional current comprising ajplurality'of Asaturable inductive devices :each vincluding a primary winding and a secondary .'winding, "means for supplying alter- V.nating .current to `the primary windings, and means for .connecting each .of said secondary .windings "to the controlmember of the lassociated .electric valve means and .the grid Aof that electric Valve means preceding it in the order of phase rotation.

3. In combination, an alternating current circuit, 'a direct current circuit, electric translating apparatus connected between said circuits and comprising an inductive network including a plurality of electrically displaced windings and a plurality of electric valves of the type employing an ionizable medium and each associated with a diiierent one of said windings and each comprising a metallic enclosing envelope, an anede, a cathode and an immersion-ignitor control member associated with said cathode, said cathode being insulated from said envelope, and a plurality of means for supplying to the control members periodic impulses of unidirectional current and each comprising a source of current including a winding having one terminal in circuit with the control member of the associated electric valve and having the other terminal connected to the envelope of that electric valve preceding it in the order of phase rotation, said envelope of that electric valve and 'the associated cathode serving as a rectifier to complete the circuit for the energization of said controlf` member.

4. In combination, an alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits and comprising an inductive network including a plurality of electrically displaced windings `and a plurality of electric valve means each associated with a different one of said windings and each comprising an anode, a cathode, an immersionignitor control member associated with the cathode and a grid insulated from said cathode and interposed in the arc discharge path between said anode and said cathode, means for supplying to the control members periodic impulses of unidirectional current, and means for connecting said last mentioned means between a control member of one electric valve and the grid of the electric valve preceding it in the order of phase rotation whereby a circuit is completed between said grid and the associated cathode to energize said control member.

5. In combination, an alternating current circuit, `a direct current circuit, electric translating apparatus connected between said circuits and comprising an inductive network including a plurality of electrically displaced windings and a plurality of electric valves of the type employing an ionizable medium and each associated with a diiTerent one of said windings and each comprising an anode, a cathode, an immersion-ignitor control member associated with the cathode and means insulated from said cathode for establishing a conducting path to the cathode through said medium when said medium is ionized, and

means connected in circuit with the control member of each of said electric valves and the insulated means of the electric valve preceding it in the order of phase rotation to maintain the potential of the control member positive with respect to the associated cathode during the entire period of conduction of that electric valve preceding it in the order of phase rotation.

6. In combination, 4an alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits and comprising an inductive network including a plurality of electrically displaced windings and a plurality of electric valves of the type employing an ionizable medium and each associated with a different one of said windings and each comprising an anode, acathode, an immersionignitor control member associated with the cathode and means insulated from said cathode for establishing a conducting path to the cathode through said medium when said medium is ionized, a plurality of excitation circuits for supplying to the control members periodic impulses of current to render said electric valves conductive in a predetermined order and during predetermined intervals of time, said excitation circuits each being connected between the control member of one electric valve and the insulated means of that electric valve preceding it in the order of phase rotation, and means for introducing into said excitation circuits components of voltage to maintain the potential of the control members positive with respect to the cathodes at least during the interval of time during which the respective excitation circuits are completed through the insulating means and the cathode of the electric valve preceding it in the order of phase rotation.

7. In combination, an alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits kand comprising an inductive network including a plurality of electrically displaced windings and a plurality of electric valves of the type einploying an ionizable medium and each associated with a different one of said windings and each comprising an anode, a cathode, an immersionignitor control member associated with the cathode and means insulated from said cathode for establishing a conducting path to the cathode through said medium when said medium is ionized, a plurality of excitation circuits each comprising a saturable inductive device having a primary winding and a secondary winding, each of said secondary windings being connected between the control member of one electric valve and the insulated means of that electric valve preceding it in the order of phase rotation, means for supplying to the primary windings alternating current, and a plurality of means for introducing into said excitation circuits components of voltage to maintain the potential of the control members positive with respect to the cathodes during intervals of time immediately preceding the normal intervals of conduction of the electric valve means.

8. In combination, an alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits and comprising an inductive network and an electric valve means having an anode, a cathode and a control member of the immersion-ignitor type associated with said cathode, an excitation circuit for energizing said control member comprising means for producing an alternating voltage of peaked wave form, and means including rectifying means for introducing into said excitation circuit a component of voltage suiiicient to neutralize a predetermined portion of the negative half cycles of said voltage of peaked wave form so that the resultant voltage impressed on said control member by said excitation circuit during a predetermined portion of the anode-cathode voltage is unidirectional.

ALBERT W. HULL. 

